VALVE SEATS AND VALVE ASSEMBLIES FOR FLUID END APPLICATIONS
In one aspect, valve seats are described herein having structure and design addressing degradative stresses encountered by valve seats during installation and operation in fluid ends. In some embodiments, a valve seat for use in a fluid end comprises a first section for insertion into a fluid passageway of the fluid end and a second section extending longitudinally from the first section, the second section has an outer diameter greater than the outer diameter of the first section. The second section also comprises a frusto-conical valve mating surface, wherein the second section is encased in a ring imparting a compressive stress condition to the second section.
The present invention relates to valve seats and valve assemblies for fluid end applications and, in particular, to valve seats comprising sintered cemented carbide components.
BACKGROUNDValves and associated valve assemblies play a critical role in fluid ends of high pressure pumps incorporating positive displacement pistons in multiple cylinders. Operating environments of the valves are often severe due to high pressures and cyclical impact between the valve body and the valve seat. These severe operating conditions can induce premature failure and/or leakage of the valve assembly. Moreover, fluid passing through the fluid end and contacting the valve assembly can include high levels of particulate matter from hydraulic fracturing operations. In hydraulic fracturing, a particulate slurry is employed to maintain crack openings in the geological formation after hydraulic pressure from the well is released. In some embodiments, alumina particles are employed in the slurry due to higher compressive strength of alumina relative to silica particles or sand. The particulate slurry can impart significant wear on contact surfaces of the valve and valve seat. Additionally, slurry particles can become trapped in the valve sealing cycle, resulting in further performance degradation of the valve assembly.
In view of these problems, valve seats have been fabricated from a variety of hard and wear resistant materials, including cemented carbide. While exhibiting high hardness and wear resistance, carbide valve seats can undergo occasional catastrophic failure due to stresses induced in the carbide from installation and removal forces, application loading and the press fit with the fluid end.
SUMMARYIn one aspect, valve seats are described herein having structure and design addressing degradative stresses encountered by the seats during installation and operation in fluid ends. In some embodiments, a valve seat for use in a fluid end comprises a first section for insertion into a fluid passageway of the fluid end and a second section extending longitudinally from the first section, the second section having an outer diameter greater than the outer diameter of the first section. The second section also comprises a frusto-conical valve mating surface, wherein the second section is encased in a ring imparting a compressive stress condition to the second section. In some embodiments, the second section is at least partially formed of sintered cemented carbide.
In another aspect, a valve seat comprises a first section for insertion into a fluid passageway of a fluid end and a second section extending longitudinally from the first section, the second section having an outer diameter greater than the outer diameter of the first section. The second section also includes a frusto-conical valve mating surface comprising sintered cemented carbide having surface roughness (Ra) of 1-15 μm. In some embodiments, the sintered cemented carbide of the valve mating surface is provided as an inlay ring coupled to a metal or alloy body. In other embodiments, the second section is formed of the sintered cemented carbide.
In another aspect, valve assemblies for use in fluid ends are provided. A valve assembly comprises a valve in reciprocating contact with a valve seat, the valve seat comprising a first section for insertion into a fluid passageway of the fluid end and a second section extending longitudinally from the first section. The second section has an outer diameter greater than the outer diameter of the first section and comprises a frusto-conical valve mating surface. The second section is also encased in a ring which imparts a compressive stress condition to the second section. In some embodiments, the second section is optionally encased in the ring, and the valve mating surface comprises sintered cemented carbide having surface roughness (Ra) of 1-15 μm. In other embodiments, the frusto-conical valve mating surface of the second section is provided as a sintered cemented carbide inlay coupled to a metal or alloy body, wherein the sintered cemented carbide has surface roughness (Ra) of 1-15 μm.
In a further aspect, fluid ends are described. A fluid end comprises a suction fluid passageway and a discharge fluid passageway. A valve assembly is positioned in at least one of the suction and discharge fluid passageways, the valve assembly comprising a valve in reciprocating contact with a valve seat. The valve seat comprises a first section for insertion into the suction or discharge fluid passageway and a second section extending longitudinally from the first section. The second section has an outer diameter greater than the outer diameter of the first section and comprises a frusto-conical valve mating surface. The second section is encased in a ring which imparts a compressive stress condition to the second section. In some embodiments, the second section is optionally encased in the ring, and the valve mating surface comprises sintered cemented carbide having surface roughness (Ra) of 1-15 μm. In other embodiments, the frusto-conical valve mating surface of the second section is provided as a sintered cemented carbide inlay coupled to a metal or alloy body, wherein the sintered cemented carbide has surface roughness (Ra) of 1-15 μm.
These and other embodiments are further described in the following detailed description.
Embodiments described herein can be understood more readily by reference to the following detailed description and examples and their previous and following descriptions. Elements, apparatus and methods described herein, however, are not limited to the specific embodiments presented in the detailed description and examples. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations will be readily apparent to those of skill in the art without departing from the spirit and scope of the invention.
In one aspect, valve seats for fluid end applications are described herein. In some embodiments, the valve seats can mitigate the severe operating conditions of hydraulic fracturing applications, leading to enhanced lifetimes and reductions in sudden seat failure. Referring now to
A second section 16 is extends longitudinally from the first section 11. The second section has an outer diameter D2 that is larger than outer diameter D1 of the first section 11. A shoulder 17 is formed by the larger outer diameter D2 of the second section 16. In the embodiment of
The second section 16 also comprises a frusto-conical valve mating surface 20, wherein the second section 16 is encased by a ring 19. In the embodiment of
In the embodiment of
As described herein, the valve seat can comprise sintered cemented carbide. In some embodiments, the first and second section of the valve seat are each formed of sintered cemented carbide. Alternatively, the first section can be formed of metal or alloy, such as steel or cobalt-based alloy, and the second section is formed of sintered cemented carbide. Forming the second section of sintered cemented carbide can impart hardness and wear resistance to the valve mating surface relative to other materials, such as steel.
In some embodiments, the second section is formed of a composite comprising sintered cemented carbide and alloy. For example, a sintered cemented carbide inlay can be coupled to a steel substrate, wherein the sintered cemented carbide inlay forms a portion or all of the valve mating surface, and the steel substrate forms the remainder of the second section. In such embodiments, the sintered carbide inlay can extend radially to contact the ring encasing the second section, thereby permitting the ring to impart a compressive stress condition to the sintered carbide inlay. In other embodiments, the steel or alloy substrate comprises a recess in which the sintered carbide inlay is positioned. In this embodiment, the outer rim of the recess is positioned between the sintered carbide inlay and ring, wherein compressive stress imparted by the ring is transmitted through the outer rim to the sintered carbide inlay.
Sintered cemented carbide of the valve seat can comprise tungsten carbide (WC). WC can be present in the sintered carbide in an amount of at least 70 weight percent or in an amount of at least 80 weight percent. Additionally, metallic binder of cemented carbide can comprise cobalt or cobalt alloy. Cobalt, for example, can be present in the sintered cemented carbide in an amount ranging from 3 weight percent to 20 weight percent. In some embodiments, cobalt is present in sintered cemented carbide of the valve seat in an amount ranging from 5-12 weight percent or from 6-10 weight percent. Further, sintered cemented carbide valve seat may exhibit a zone of binder enrichment beginning at and extending inwardly from the surface of the substrate. Sintered cemented carbide of the valve seat can also comprise one or more additives such as, for example, one or more of the following elements and/or their compounds: titanium, niobium, vanadium, tantalum, chromium, zirconium and/or hafnium. In some embodiments, titanium, niobium, vanadium, tantalum, chromium, zirconium and/or hafnium form solid solution carbides with WC of the sintered cemented carbide. In such embodiments, the sintered carbide can comprise one or more solid solution carbides in an amount ranging from 0.1-5 weight percent.
In some embodiments, a single grade of sintered cemented carbide can be employed to form the first and second sections of the valve seat. In other embodiments, one or more compositional gradients can exist between sintered cemented carbide of the first section and second section. For example, sintered cemented carbide of the first section may have larger average grain size and/or higher metallic binder content to increase toughness. In contrast, sintered cemented carbide of the second section may have smaller average grain size and less binder for enhancing hardness and wear resistance. Additionally, a compositional gradient can exist within the first and/or second section of the valve seat. In some embodiments, sintered cemented carbide forming the valve mating surface comprises small average grain size and lower metallic binder content for enhancing hardness and wear resistance. Progressing away from the valve mating surface, the sintered cemented carbide composition of the second section can increase in grain size and/or binder content to enhance toughness and fracture resistance. In some embodiments, for example, sintered cemented carbide of high hardness and high wear resistance can extend to a depth of 50 μm-1 mm or 75-500 μm in the second section. Once the desired depth is reached, the sintered cemented carbide composition changes to a tougher, fracture resistant composition.
When the valve mating surface is formed of sintered cemented carbide, the sintered cemented carbide can have surface roughness (Ra) of 1-15 μm, in some embodiments. Surface roughness (Ra) of the sintered cemented carbide can also be 5-10 μm. Surface roughness of sintered cemented carbide forming the valve mating surface may be obtained via mechanical working including, but not limited to, grinding and/or blasting techniques. Moreover, sintered cemented carbide forming the second section of the valve seat, including the valve mating surface, can exhibit a compressive stress condition of at least 500 MPa. In some embodiments, sintered cemented carbide forming the second section can have a compressive stress condition selected from Table I.
Compressive stress condition of the sintered cemented carbide can result from compression imparted by the ring encasing the second section and/or mechanically working the sintered cemented carbide to provide a valve mating surface of desired surface roughness. Compressive stress of the sintered cemented carbide may be determined via X-ray diffraction according to the Sin2ψ method. Sintered cemented carbide of the valve seat may also exhibit hardness of 88-94 HRA.
The ring encasing the second section can be formed of any suitable material operable to impart a compressive stress condition to the second section. In some embodiments, the ring is formed of metal or alloy, such as steel. The ring may also be formed of ceramic or cermet.
In another aspect, a valve seat comprises a first section for insertion into a fluid passageway of a fluid end and a second section extending longitudinally from the first section, the second section having an outer diameter greater than the outer diameter of the first section. The second section also includes a frusto-conical valve mating surface comprising sintered cemented carbide having surface roughness (Ra) of 1-15 μm. The second section of the valve seat may optionally be encased by a ring as described herein.
Alternatively, the frusto-conical valve mating surface can be provided as a sintered cemented carbide inlay coupled to a metal or alloy body, wherein the sintered cemented carbide has surface roughness (Ra) of 1-15 μm.
In another aspect, valve assemblies for use in fluid ends are provided. A valve assembly comprises a valve in reciprocating contact with a valve seat, the valve seat comprising a first section for insertion into a fluid passageway of the fluid end and a second section extending longitudinally from the first section. The second section has an outer diameter greater than the outer diameter of the first section and comprises a frusto-conical valve mating surface. The second section is also encased in a ring which imparts a compressive stress condition to the second section. In some embodiments, the second section is optionally encased in the ring, and the valve mating surface comprises sintered cemented carbide having surface roughness (Ra) of 1-15 μm. In other embodiments, the frusto-conical valve mating surface of the second section is provided as a sintered cemented carbide inlay coupled to a metal or alloy body, wherein the sintered cemented carbide has surface roughness (Ra) of 1-15 μm. In some embodiments, the metal or alloy body forms the first section of the valve seat and provides a recess for the sintered cemented carbide inlay in the second section. The valve seat can have any features, composition and/or properties described herein.
In a further aspect, fluid ends are described. A fluid end comprises a suction fluid passageway and a discharge fluid passageway. A valve assembly is positioned in at least one of the suction and discharge fluid passageways, the valve assembly comprising a valve in reciprocating contact with a valve seat. The valve seat comprises a first section for insertion into the suction or discharge fluid passageway and a second section extending longitudinally from the first section. The second section has an outer diameter greater than the outer diameter of the first section and comprises a frusto-conical valve mating surface. The second section is encased in a ring which imparts a compressive stress condition to the second section. In some embodiments, the second section is optionally encased in the ring, and the valve mating surface comprises sintered cemented carbide having surface roughness (Ra) of 1-15 μm. In other embodiments, the frusto-conical valve mating surface of the second section is provided as a sintered cemented carbide inlay coupled to a metal or alloy body, wherein the sintered cemented carbide has surface roughness (Ra) of 1-15 μm. In some embodiments, the metal or alloy body forms the first section of the valve seat and provides a recess for the sintered cemented carbide inlay in the second section. The valve seat can have any features, composition and/or properties described herein. In some embodiments, the compressive stress condition of the first section is substantially equal to the compressive stress condition of the second section. In being substantially equal, compressive stress conditions of the first and second sections are within 10 percent of one another.
Various embodiments of the invention have been described in fulfillment of the various objectives of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention.
Claims
1. A valve seat for use in a fluid end comprising:
- a first section for insertion into a fluid passageway of the fluid end; and
- a second section extending longitudinally from the first section, the second section having a compressive stress condition and an outer diameter greater than outer diameter of the first section and comprising a frusto-conical valve mating surface, wherein the second section is encased in a ring imparting the compressive stress condition to the second section and the first section comprises an outer surface for engaging the fluid passageway.
2. The valve seat of claim 1, wherein the ring has a concentric arrangement with an outer surface of the second section.
3. The valve seat of claim 1, wherein the ring comprises a metal or alloy.
4. The valve seat of claim 1, wherein the ring is outside the frusto-conical valve mating surface.
5. The valve seat of claim 1, wherein the second section comprises sintered cemented carbide.
6. The valve seat of claim 1 further comprising a shoulder between the first section and second section.
7. The valve seat of claim 6, wherein the ring at least partially covers the shoulder.
8. The valve seat of claim 5, wherein the sintered cemented carbide has compressive residual stress of at least 1 GPa.
9. The valve seat of claim 5, wherein the first section comprises the sintered cemented carbide.
10. The valve seat of claim 5, wherein the valve seat mating surface is at least partially formed of the sintered cemented carbide.
11. The valve seat of claim 10, wherein the sintered cemented carbide of the valve mating surface is mechanically worked.
12. The valve seat of claim 11, wherein the sintered cemented carbide of the valve mating surface has an average surface roughness of 1-15 Ra.
13. The valve seat of claim 10, wherein the sintered cemented carbide of the valve mating surface is in the form of an inlay ring.
14. The valve seat of claim 1, wherein the first section and second section are formed of sintered cemented carbides of differing composition.
15. The valve seat of claim 1, wherein the second section is formed of sintered cemented carbide having a compositional gradient along thickness of the second section.
16. The valve seat of claim 1, wherein the first section is formed of metal or alloy and the second section is formed of sintered cemented carbide.
17. The valve seat of claim 14, wherein the sintered cemented carbide of the second section has higher hardness and/or wear resistance than the sintered cemented carbide of the first section.
18. A valve assembly for use in a fluid end comprising:
- a valve in reciprocating contact with a valve seat, the valve seat comprising a first section for insertion into a fluid passageway of the fluid end and a second section extending longitudinally from the first section, the second section having a compressive stress condition and an outer diameter greater than outer diameter of the first section and comprising a frusto-conical valve mating surface, wherein the second section is encased in a ring imparting the compressive stress condition to the second section and the first section comprises an outer surface for engaging the fluid passageway.
19. The valve assembly of claim 18, wherein the first section and the second section comprise sintered cemented carbide.
20. The valve assembly of claim 18, wherein the first section is formed of metal or alloy and the second section is formed of sintered cemented carbide.
21. The valve assembly of claim 18, wherein the ring has a concentric arrangement with an outer surface of the second section.
22. A fluid end comprising:
- a suction fluid passageway and a discharge fluid passageway; and
- a valve assembly in at least one of the suction and discharge fluid passageways, the valve assembly comprising a valve in reciprocating contact with a valve seat, the valve seat comprising a first section for insertion into the suction or discharge fluid passageway and a second section extending longitudinally from the first section, the second section having a compressive stress condition and an outer diameter greater than outer diameter of the first section and comprising a frusto-conical valve mating surface, wherein the second section is encased in a ring imparting the compressive stress condition to the second section and the first section comprises an outer surface for engaging the fluid passageway.
23. The fluid end of claim 22, wherein the compressive stress condition of the second section is substantially equal to a compressive stress condition of the first section.
24. The fluid end of claim 22, wherein the first and second sections comprise sintered cemented carbide.
25. The fluid end of claim 22, wherein the second section is formed of sintered cemented carbide, and the valve mating surface has surface roughness (Ra) of 1-15 μm.
26. A valve seat for use in a fluid end comprising:
- a first section for insertion into a fluid passageway of the fluid end;
- a second section extending longitudinally from the first section, the second section having an outer diameter greater than outer diameter of the first section and comprising a frusto-conical valve mating surface; and
- a ring encasing only the second section, wherein the second section comprises a compressive stress condition imparted by the ring.
27. The valve seat of claim 26, wherein the first and second sections have an unequal stress condition.
28. The valve seat of claim 1, wherein the first and second sections have an unequal stress condition.
Type: Application
Filed: Jan 19, 2018
Publication Date: Jul 25, 2019
Inventors: Roger M. STARK (Jefferson Hills, PA), Carrie Bartkowiak (Traverse City, MI), John Brosnahan (North Huntingdon, PA), Michael Kelly (Anaheim, CA)
Application Number: 15/875,758